Having been conventionally available is an operation input device giving a predetermined tactile sensation to the finger tip of a user making a touch operation, by vibrating a touch panel on which the user makes the touch operation at a frequency within the ultrasound range.
An example of a literature related to such a technology includes Japanese Laid-open Patent Publication No. 2016-170766.
However, such an operation input device sometimes emits strange sound due to the interference between the vibrating touch panel and the fingerprint of the finger tip touching the touch panel.